1. Field of the Invention
The present invention relates to an on-screen display signal processing device which is adapted for use with television sets employing digital display devices, such as liquid crystal panels, plasma display panels (PDPs), etc.
2. Description of the Related Art
Television sets are provided with an on-screen display (OSD) signal processing circuit. The OSD signal processing device has a memory previously stored with given characters and graphic data which are displayed at mode and channel switching times. With analog television sets, the characters and graphic data are converted into digital form and then applied to a picture signal combining circuit.
In recent years, television sets containing digital flat-panel display devices, such as liquid crystal panels, plasma display panels (PDPs), etc., have become widespread. In the case of these television sets, in order to obtain OSD signals to be applied to the flat-panel display devices, original OSD signal processing devices have been developed. See, for example, Japanese Unexamined Patent Publications Nos. 10-031454 and 2001-343964.
In future, principal television sets will be those containing digital display devices, such as liquid crystal panels, plasma display panels, etc. The development of a new original OSD signal processing circuit adapted for digital processing under such a circumstance would result in a considerable increase in the cost of the television sets. In addition, conventional OSD signal processing circuits adapted to provide analog outputs would fall into disuse, leading to a waste of resources.
Up to now, various OSD signal generating circuits have been developed and manufactured. OSD signals include channel number display signals and menu display signals. Remanufacturing these circuits into circuits adapted for the digital television sets would involve considerable cost and time.